I do not know why, but using single quotes instead of doubles did solve my problem!
See the difference: $testReplace2 = "<div id='pos1-0'><img name='pos1-0' src='test.gif' height='50' width='50' border='0' alt='white_pawn'></img></div>"; $testReplace2 = '<div id="pos1-0"><img name="pos1-0" src="test.gif" height="50" width="50" border="0" alt="white_pawn"></img></div>';